Excitations below the Kohn mode; FIR-absorption in quantum dots

Vidar Gudmundsson*, Roman Krahne, Christian Heyn, Detlef Heitmann

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

1 Citation (Scopus)


We have investigated the far-infrared (FIR) responses of an array of quantum dots in modulation doped GaAs heterostructures in an external magnetic field. In accordance with the extended Kohn theorem FIR-radiation can only excite the center-of-mass modes of harmonically confined electrons in a dot. In a perpendicular magnetic field the single absorption peak corresponding to the Kohn mode splits in two peaks separated by the cyclotron frequency. We observe novel modes at frequencies below the higher frequency Kohn mode. Comparison with Hartree-RPA calculations show that these modes arise from the flattened confining potential in our field-effect quantum dots. They reflect t pronounced relative motion of the charge density with respect to its center-of-mass.

Original languageEnglish
Pages (from-to)136-139
Number of pages4
JournalPhysica Scripta T
Publication statusPublished - 2002
EventProceedings of the 19th Nordic Semiconductor Meeting - Lyngby, Denmark
Duration: 20 May 200123 May 2001


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